Public Release: 

Clean water and soap may help improve growth in young children

London School of Hygiene & Tropical Medicine

Improving water quality and hygiene practices may improve the growth of children, according to a new report. The Cochrane review - authored by the London School of Hygiene & Tropical Medicine and WaterAid - found evidence of small but significant improvements in growth of children under the age of five who have access to clean water and soap.

Researchers identified 14 studies conducted in low and middle income countries (Bangladesh, Ethiopia, Nigeria, Chile, Guatemala, Pakistan, Nepal, South Africa, Kenya and Cambodia) that provided data on the effect of water, sanitation and hygiene programmes on the physical growth of 9,469 children. The authors' analysis of the data suggested that interventions to improve the quality of the water in the household and provide soap resulted in an average 0.5cm increased height growth in children under the age of five.

Report lead author Dr Alan Dangour, a public health nutritionist from the London School of Hygiene & Tropical Medicine, said: "We typically think that providing clean water, sanitation and hygiene is an effective way to reduce the incidence and associated deaths from diseases such as diarrhoea - which remains the third biggest killer of under fives worldwide. For the first time our analysis suggests that better access to these services may also have a small but important impact on the growth of young children.

"While there are some important shortcomings in the available evidence base, we estimate that clean drinking water and effective hand washing could reduce the prevalence of stunting in children under the age of five by up to 15%.1 This is potentially an extremely important finding, that identifies that improving access to water, sanitation and hygiene could be a key part of the tool kit to tackle the global burden of undernutrition."

Poor height growth, or stunting, affects 165 million children worldwide and results in long term impacts on physical and mental development, increasing the risk of mortality and reducing productivity in adulthood.2 Undernutrition is a cause of 3.1 million deaths annually - nearly half (45%) of all deaths in children under five.2

International development funding supports many nutritional interventions, such as the provision of vitamin supplements, that directly tackle poor nutrition outcomes, but this is the first study to show that interventions in water, sanitation and hygiene could also play a role in improving nutritional outcomes for children.

WaterAid chief executive Barbara Frost said: "As well as resulting in hundreds of thousands of under-five deaths every year, there is a growing consensus that unsafe water, inadequate sanitation and poor hygiene can affect the body's ability to absorb nutrients, impacting on child development and contributing to their stunting.

"Stunting continues to have serious consequences on the social and economic outcomes of developing countries. With only £1.57 ($2.39) a year provided in aid for water and sanitation per person in sub-Saharan Africa - less than the price of a cup of coffee - we have to make access to these life critical necessities a higher priority."

The authors say that improving access to clean water and soap is likely to have led to the increase in height because of the reduction in microbiological and parasitic infestations in early childhood, which can negatively impact growth.

Professor Tim Wheeler, Deputy Chief Scientific Adviser to the Department for International Development, which funded the research, said: "Failure to get the right nutrition in childhood can cause lifelong damage that cannot be undone. This report provides further support to the idea that using clean water and soap remains one of the best ways to prevent contracting diarrhoea and stopping young children losing the essential nutrients vital for them to grow."

Commenting on the research, Dr Francesco Branca, Director of Nutrition for Health and Development at the World Health Organization, who was not involved in the study, said: "Until now, we have not had a demonstration of the direct nutrition impact of WASH interventions on nutrition. This review shows that a multi-pronged approach is the way to go--bringing together actions to improve food quality and safety as well as feeding and care of children, with others to prevent and treat infections and improve the home environment--to address the scourge of chronic malnutrition."

The authors note there are limitations in the available data for analysis as the main findings of the review are based on relatively short-term studies (9-12 months in duration) and none of these studies is of high methodological quality. There are several large ongoing studies that my help improve the quality of the evidence base. The research was funded by the Department for International Development via the SHARE Research Consortium.


For more information or to request interviews, please contact the London School of Hygiene & Tropical Medicine press office on or +44 (0)207 927 2802, or Hratche Koundarjian, at the WaterAid media team on or +44 (0)207 793 4909 / +44 (0)7905 911 039.

Notes to editors:

  • Dangour AD, Watson L, Cumming O, Boisson S, Che Y, Velleman Y, Cavill S, Allen E, Uauy R. Interventions to improve water quality and supply, sanitation and hygiene practices, and their effects on the nutritional status of children. Cochrane Database of Systematic Reviews 2013. DOI: 10.1002/14651858.CD009382.pub2.

  • A copy of this Cochrane review is available to media under embargo upon request to or Once published, the review will be available at

  • A new briefing, Under-nutrition and water, sanitation and hygiene, has been produced by WaterAid, the SHARE Research Consortium, and the London School of Hygiene & Tropical Medicine, and is available under the above embargo at:

  • Photos available for media to usage at

  • References:

    1. At baseline, 28.7% of the sample in the meta-analysis that received the intervention were stunted. After the intervention the authors estimate that 24.2% of the sample were stunted i.e. an absolute decline in stunting prevalence of 4.5 percentage points. This is equivalent to a 15.7% relative decline [(4.5/28.7)*100] in stunting prevalence in the sample.
    2. Black R, Victoria C, Walker S,Bhattu Z, Christian P, Onis M, Ezzati M, Grantham-McGregor S, Katz J, Martorell R, Uauy R. Maternal and child undernutrition and overweight in low-income and middle-income countries. Lancet. DOI: 10.1016/S0140-6736(13)60937-X

  • Report co-authors Velleman and Cavill are employees of WaterAid, an international non-governmental organisation that works to promote the provision of safe water, improved sanitation and hygiene globally. They were involved in the conceptualisation of the review, contributed to the literature search and provided comments on the review drafts but were not involved in data extraction, data analysis or interpretation of the findings.

  • The views expressed in this research do not necessarily reflect those of the funders, the Department of International Development.

  • The SHARE research consortium is led by the London School of Hygiene & Tropical Medicine in partnership with the International Centre for Diarrhoeal Disease Control, Bangladesh, the International Institute for Environment and Development, Shack/Slum Dwellers International, and WaterAid.

About WaterAid

WaterAid's vision is of a world where everyone has access to safe water and sanitation. The international organisation works in 28 countries across Africa, Asia, Central America and the Pacific region to transform lives by improving access to safe water, hygiene and sanitation in some of the world's poorest communities. Over the past 32 years, WaterAid has reached 19.2 million people with safe water and, since 2004, 15.1 million people with sanitation.

For more information, visit, follow @wateraid on Twitter or visit us on Facebook at

  • 768 million people in the world do not have access to safe water. This is around 1 in 10 people worldwide.

  • 2.4 billion people in the world do not have access to adequate sanitation. This is around 1 in 3 people worldwide.

About the London School of Hygiene & Tropical Medicine

The London School of Hygiene & Tropical Medicine is a world-leading centre for research and postgraduate education in public and global health, with 3,500 students and more than 1,000 staff working in over 100 countries. The School is one of the highest-rated research institutions in the UK, and was recently cited as one of the world's top universities for collaborative research. The School's mission is to improve health and health equity in the UK and worldwide; working in partnership to achieve excellence in public and global health research, education and translation of knowledge into policy and practice.

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